Bulldozer stabilizer linkage

ABSTRACT

A blade stabilizing linkage for an earth-working vehicle such as a bulldozer. The linkage is employed in an earth-working vehicle having a frame, a pair of push arms pivotally secured to the frame and a blade pivotally mounted on the push arms. The linkage interconnects the front of the frame and the rear of the blade. The linkage comprises a first link pivotally connected to the front of the frame for pivotal movement about a first pivot axis and a second link pivotally connected to the rear of the blade for movement about a second pivot axis transverse to the first pivot axis. The links are connected to each other by a universal joint. The linkage maximizes stabilization of the blade against lateral shifting for vertical, tilting and angular movement of the blade relative to the frame.

United States Patent [1 1 Eftefield Aug. 26, 1975 BULLDOZER STABILIZER LINKAGE Larry G. Eftefield, .Ioliet, Ill.

[73] Assignee: Caterpillar Tractor Company,

Peoria, 111'.

221 Filed: June 28,1974

21 Appl. No.: 483,914

[75] Inventor:

[52] US. Cl. 172/804; 172/805; 172/809 [51] int. C1. E02F 3/76 [58] Field of Search 172/803, 804809, 172/801, 802

[56] References Cited UNITED STATES PATENTS 2,624,131 l/l953 Rockwell 172/801 X 3,222,804 12/1965 Kuhl 172/801 X 3,234,670 2/1966 Frycr et a1. 172/803 3,656,558 4/1972 Kolinger 172/803 3,743,032 7/1973 Schiclc i 172/803 Primary ExaminerStephen C. Pellegrino Attorney, Agent, or Firm-Ralph E. Walters [57] ABSTRACT A blade stabilizing linkage for an earth-working vehicle such as a bulldozer. The linkage is employed in an earth-working vehicle having a frame, a pair of push arms pivotally secured to the frame and a blade pivotally mounted on the push arms. The linkage interconnects the front of the frame and the rear of the blade. The linkage comprises a first link pivotally connected to the front of the frame for pivotal movement about a first pivot axis and a second link pivotally connected to the rear of the blade for movement about a second pivot axis transverse to the first pivot axis. The links are connected to each other by a universal joint. The linkage maximizes stabilization of the blade against lateral shifting for vertical, tilting and angular movement of the blade relative to the frame.

6 Claims, 5 Drawing Figures PATENTED AUGZ 6 I975 SWEET l 2 BULLDOZER STABILIZER LINKAGE BACKGROUND OF THE INVENTION This invention relates to earth-working vehicles and, more specifically, to blade stabilizing linkages in earthworking vehicles such as bulldozers.

The most pertinent prior art known to the applicant includes US. Pat. Nos. 1,997,001; 2,225,393; 3,356,600; 2,624,131; 2,868,579; 3,222,804; and 3,234,670.

Earth-working vehicles equipped with bulldozer blades typically have a main vehicle frame flanked by track frames. The bulldozing blade is typically pivotally mounted forwardly of the front end of the main frame on long push arms which extend substantially rearwardly and flank the track frames. The push arms are pivotally connected to the track frames near the rear of the vehicle.

In order to maintain the vehicle as compact as possi ble, the push arms are spaced but a short distance from the adjacent track frames. Such spacing must be main tained or else injurious contact between the track on a track frame and the push arms would result. Such contact is a distinct possibility due to the substantial stresses that are developed in the operation of such tractors. The stresses are large due to the powerful tractive effort of the vehicles as well as the frequency of off-center loading of the blade. Moreover, directional changes of the vehicle when the blade is engaged with the earth similarly can produce large forces that would. cause lateral shifting of the blade to the point that such contact could occur if means were not taken to prevent such contact.

Typically. a blade stablizing linkage is employed to interconnect the main frame of the vehicle and the blade to minimize such lateral shifting to the point where injurious contact of the type mentioned previously cannot occur. However, by their very nature, such linkages have impeded provision of other desirable features in connection with blade mounting on the tractor. For example, many such linkages permit only vertical and tilting movement of the blade relative to the vehicle. Others are extremely bulky as, for example, in extending substantially rearwardly to a pivot axis coextensive with the pivot axis of the push arms to their point of connection to the track frames.

Others, cannot be adapted to permit vertical, tilting and angling movement of the blade relative to the vehicle frame without undesirably increasing the clearance between the push arms and the track frames required to prevent contact between the push arms and the tracks.

SUMMARY OF THE INVENTION It is the principal object of the invention to provide a new and improved bulldozer blade stabilizing structure. More specifically, it is an object of the invention to provide such a linkage wherein lateral shifting of the blade relative to a vehicle frame is minimized during even the most severe stresses placed thereon so that undesirably large clearances need not be provided between vehicle componcnts and yet which will permit the blade to be moved through vertical, tilting and angular movements relative to the frame.

An exemplary embodiment of the invention achieves the foregoing object in an earth-working vehicle having a frame, a pair of push arms pivotally secured at one end to the frame, a blade pivotally secured to the push arms at the other ends thereof with a stabilizing linkage comprising two links. A first of the links is pivotally connected to the front end of the frame for pivotal movement thereon about a first pivot axis. The second of the links is pivotally connected to the rear of the blade for pivotal movement relative thereto about a second pivot axis which is transverse to the first pivot axis. The links are then interconnected by a universal connection.

According to the preferred embodiment of the invention, one of the pivot axes is vertical and the other pivot axis is horizontal. The universal connection comprises a ball joint.

Where the vehicle is of the type wherein the blade is pivotally connected to the push arms for movement about two mutually perpendicular axes, the foregoing linkage stabilizes the blade against substantial lateral movement during vertical, tilting, tipping, and angling movement of the blade relative to the vehicle.

In a highly preferred embodiment of the invention, the first mentioned link, which is pivotally connected to the vehicle frame, has a length just slightly less than the distance between the front end of the frame and the back of the blade so that the second link, in many positions of the blade relative to the frame, is substantially parallel to the blade. This structure permits use of relatively short linkages that afford substantial stabilization and yet which may be easily serviced when required.

Other objects and advantages of the invention will become apparent from the following specification taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an earth-working vehicle embodying the invention;

FIG. 2 is an enlarged, fragmentary side elevation of the vehicle;

FIG. 3 is an enlarged, fragmentary view of one form of linkage made according to the invention;

FIG. 4 is an enlarged, fragmentary view of a second form of linkage made according to the invention; and

FIG. 5 is a somewhat schematic plan view of the invention illustrating angling of the blade relative to a vehicle frame.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exemplary embodiment of an earth-working vehi cle made according to the invention is illustrated in FIGS. 1 and 2 and is seen to include a vehicle, generally designated 10, having a main frame 12 flanked by a pair of track frames 14. Drive components, generally designated 16, are driven by an engine (not shown) and, in turn, drive chain drive sprockets 18 which, in turn, drive track chains 20. As is well known, track roller assemblies 24 may be provided on each of the track frames l4for engaging the lower run of each track chain 20.

Forwardly of the front end 26 of the frame 12 is a bulldozer blade, generally designated 28. The blade 28 is secured to the vehicle 10 by means ofa pair of clevis type connections 30 at opposite sides thereof located near the lower end of the blade 28 and on the back thereof to push arms 32 which flank the track frames 14. As will be recognized by those skilled in the art, the

connections 30 provide for pivotal mounting of the blade 28 on the push arms 32 for movement about two mutually perpendicular axes. The ends of the push arms 32 opposite from the connection 30 are pivotally connected to trunnions 34 which, in turn, are secured to the track frames 14. Bearings 36 of any suitable type may be provided.

Each track frame 14 also mounts an L-shaped frame 38 which, at one end, pivotally mounts, by means of a pin 40, a triangular bellcrank 42. The other end of the frame 38 pivotally mounts, as by a pin 44, a hydraulic cylinder 46 which has its piston rod 48 pivotally connected as by a pin 50 to the bellcrank 42. The bellcrank 42 is pivotally connected as by a pin 52 to a link 54 which in turn is pivotally connected by a pin 56 to a bracket 58 secured to the corresponding push arm 32. The bracket 56 also mounts a further pivot pin 60 which pivotally mounts one end of a hydraulic cylinder 64. The rod end 62 of the hydraulic cylinder 64 is connected by a clevis type mounting similar to that illustrated at 30 to the upper rear end of the blade 28.

From the foregoing, it will be recognized that through appropriate control of the cylinder 46, the vertical attitude of the blade 28 relative to the frame may be varied. Simiarly, by appropriate control of the cylinder 64, the blade 28 may be made to tilt relative to the frame. Of course, if such tilting movement is not required, the cylinders 64 may be replaced with struts.

Referring now to FIG. 5, the invention also contemplates the use of selectively extendable push arms 32. In this embodiment of the invention, each push arm is made up of two sections including a first tubular section 70 which may be telescopingly received in a second tubular section 72. The former is secured by a suitable pivot to the track frame 14, while the latter is secured as by the previously described clevis to the back of the blade. Within the member 70 is a hydraulic cylinder 74 pivotally secured by a pivot pin 76 in any suitable fashion to a suitable bracket on the interior of the member 70. The rod 78 of the cylinder 74 is pivotally secured as by pin 80 to any suitable bracket within the interior of the member 72. Thus, by appropriate control of the cylinders 74, the blade 28 may be angled with respect to the frame as illustrated in FIG. 5.

Referring to FIGS. l-S, a stabilizing means, generally designated 100, is interposed between the front end 26 of the frame 12 and the back of the blade 28. With reference to the various Figs, particularly to FIG. 3, one form of stabilizing linkage 100 is seen to consist of an A-frame type of link 102, having its legs connected as by pivot pins 104 to ears 106 secured to the front end of the tractor frame 12. As will be appreciated, the pivot pins 104 provided for rotation of the link 102 about a substantially horizontal axis. The link 102 has a length just slightly less than the distance between the front end 26 of the frame and the rear side of the blade A second link 110 has one end pivotally connected as by a pin 112 to rearwardly extending ears 114 on the back of the blade 28. The pivot axis defined by the pin 112 is transverse to the pivot axis defined by the pins 104, i.e., vertical, and the arrangement is such that the link 110 is generally parallel to the rear side of the blade 28. The ends of the links 102 and 110 remote from their respective pivot pins 104 and 112 are universally connected together. Preferably, a ball joint 116 is employed for this purpose.

Still another form of linkage embodying the invention is illustrated in FIG. 4. According to the embodiment of FIG. 4, forwardly extending ears 120 secured to the front end 26 of the vehicle frame 12 mount a pivot pin 122, which, in turn, pivotally impales one end of a link 124. The opposite end of the link 124 mounts the ball element 126 of the ball joint which is completed by the apex 128 of an A-frame link 130. The legs of the A-frame link 130 are pivotally connected as by pins 132 to rearwardly extending ears 134 on the back of the blade 28. Again, the arrangement is such that the pivot axis defined by pivot 122 is transverse to the pivot axis defined by the pins 132, the link 130 is slightly less in length than the distance between the blade and the frame front, and the link 124 is generally parallel to the blade 28,

As a result of the foregoing structure, it will be appreciated that the blade 28 may be moved vertically, through tilting and angular positions, with respect to the vehicle frame. Examples of vertical and angular movement are illustrated in FIGS. 2 and 5 and it will be recognized that the stabilizing means of the invention provide substantial resistance to lateral movement of the blade 28 due to the variety of stresses encountered in operation and yet accommodate universal blade movement with respect to the frame. It will also be recognized that the components of the stabilizing means 100 are simple in nature and readily accessible for servicing by reason of their exposure.

Moreover, because the first link, i.e., that secured to the tractor frame, is chosen to have a length just slightly less than the usual distance between the front end of the frame and the back of the blade 28, relatively short links may be employed so that there is minimal deflection and maximum stabilization.

Thus, it will be appreciated that stabilizing means made according to the invention accomplish the object previously set forth.

I claim:

1. In an earth-working vehicle having a frame, a pair of push arms pivotally secured at one end to the frame, a blade pivotally secured to the push arms at the ends thereof remote from their pivotal connection to the frame and just forwardly of the front end of the frame, and blade stabilizing means interconnecting the blade and the frame for minimizing lateral movement of the blade with respect to the frame, the improvement wherein said stabilizing means comprise:

a single first link pivotally secured to the frame front end for movement about a first pivot axis;

a second link pivotally connected to the blade for movement about a second pivot axis transverse to said first pivot axis; and

means connecting said links to each other for relative universal movement.

2. An earth-working vehicle according to claim 1 wherein one of said pivot axes is vertical and the other of said pivot axes is horizontal.

3. An earth-working vehicle according to claim 1 wherein said connecting means comprises a ball joint.

4. An earth-working vehicle according to claim 1 wherein said blade is substantially pivotally connected to both said push arms for rotation about two mutually perpendicular axes whereby said blade stabilizing means stabilizes said blade against substantial lateral movement during vertical, tilting and angling movement of the blade relative to the vehicle.

5. An earth-working vehicle according to claim 1 6. An earth-working vehicle according to claim 1 furwherein said first link has a length just slightly less than ther including means whereby the effective length of at the distance between the front end of the frame and the least one of said push arms may be varied. back of the blade. 

1. In an earth-working vehicle having a frame, a pair of push arms pivotally secured at one end to the frame, a blade pivotally secured to the push arms at the ends thereof remote from their pivotal connection to the frame and just forwardly of the front end of the frame, and blade stabilizing means interconnecting the blade and the frame for minimizing lateral movement of the blade with respect to the frame, the improvement wherein said stabilizing means comprise: a single first link pivotally secured to the frame front end for movement about a first pivot axis; a second link pivotally connected to the blade for movement about a second pivot axis transverse to said first pivot axis; and means connecting said links to each other for relative universal movement.
 2. An earth-working vehicle according to claim 1 wherein one of said pivot axes is vertical and the other of said pivot axes is horizontal.
 3. An earth-working vehicle according to claim 1 wherein said connecting means comprises a ball joint.
 4. An earth-working vehicle according to claim 1 wherein said blade is substantially pivotally connected to both said push arms for rotation about two mutually perpendicular axes whereby said blade stabilizing means stabilizes said blade against substantial lateral movement during vertical, tilting and angling movement of the blade relative to the vehicle.
 5. An earth-working vehicle according to claim 1 wherein said first link has a length just slightly less than the distance between the front end of the frame and the back of the blade.
 6. An earth-working vehicle according to claim 1 further including means whereby the effective length of at least one of said push arms may be varied. 